The present invention relates to ventilator apparatus, and more particularly but not exclusively to so-called xe2x80x9ccuirass ventilatorsxe2x80x9d.
Where a patient requires assistance in breathing, it is often preferable to use a ventilator apparatus external to the body rather than using intubation of the patient. Known ventilator apparatus includes the xe2x80x9ciron lungxe2x80x9d type in which the torso of the patient is fully enclosed within the iron lung, and the cuirass ventilator which consists generally of a turtle shell-like enclosure which is applied to the front of the trunk of the patient and, when associated with an air oscillator, which provides breathing assistance.
The peripheral edge region of the shell of the cuirass ventilator requires to be substantially sealed to the skin of the patient both during the inhalation and expiration phases. One solution to provision of the requisite seal has been to make a shell which is tailored to the individual patient. However, this is expensive and time-consuming. Another technique has been to provide a large number of different standard sizes of shell, each provided for example with a foam-type sealing means about the periphery, and to form the shell of the material which, while being sufficiently rigid to allow the correct breathing action, is sufficiently flexible that the periphery will conform to the contours of the patient in question. Other arrangements include those disclosed in GB Application No 8900871. Yet another ventilator is disclosed in GB Application No 8618254. This latter document discloses a ventilator apparatus comprising a shell with a sealing member between the shell and the patients body, the sealing member having the form of a pleated flexible curtain which is capable of being drawn sealingly against the patients body by straps.
The present applicant has carried out research in the field of ventilator apparatus and has a number of patent applications including EP-A-506467, EP-A-0379049, EP-A-0258302, EP-A-0373153 and EP-A-0192337.
A number of problems exist with prior solutions, for example a relative large number of different sizes of shell are required. Furthermore, the resilience of the shell which is typically applied to the patient by straps around the patient""s back, may cause discomfort to the patient. The selection of materials to provide the desired degree of resilience is difficult and the resilient performance of the shell may degrade over a period of use.
From the point of view of the patient and of medical staff attending the patient, prior ventilators may cause chafing or ulceration at certain points, for example, in the arm pit region of the patent, at the transition between a portion of the ventilator shell which runs across the chest to a portion of the ventilator shell which runs along the side of the chest, down the patients body. The consequence of this may be a frequent need to attend to the patient by medical staff to prevent such chafing from causing ulceration.
Where a sealing flap has been provided in the prior art, it has been found difficult to provide adequate performance in the transition region of the seal between the region across the patients chest and the region running down the patients trunk, which transition region typically lies near to the arm pit of the patient. In the region of the sealing flap which runs across the patients chest, the sealing flap is required to seal in a generally downwardly, with respect to a surface on which the patient is lying, direction whereas in the sealing region which runs along the patients trunk, the sealing pressure is exerted generally transverse to such a surface, in other words in a perpendicular direction to that for the seal across the patients chest. The above-mentioned transition region therefore runs between these two regions and across the transition region the direction of sealing pressure varies. This feature, together with the varying geometry of the body associated with this transition region frequently leads to the sealing flap tearing, in use, and, even if tearing does not occur, the pressure in the area around the arm pit can cause discomfort to the patient which may lead to skin ulcers or pressure sores if the patients position is not moved fairly frequently, for example more than every four hours.
It would be desirable to provide an improved sealing device which provides a greater degree of conformability to the contours of a patient. Such a sealing device would enable a smaller number of standard sizes of shells to be stocked and would substantially reduce patient discomfort. As the conformability of the ventilator could be provided by the sealing device rather than by the material of the ventilator shell itself, the choice of material for the shell is not restrictive as in prior art devices.
It would also be desirable to provide a cuirass ventilator in which the above-mentioned propensity to chafing is at least reduced, or is eliminated. With such a ventilator apparatus, the Unsealing engagement pressure in the armpit region of the patient would be reduced, thereby reducing discomfort and eliminating any tearing of the seal while at the same time maintaining the ventilator air pressure.
It would also be desirable to provide a sealing device which requires a lower seal engagement pressure in the above-mentioned transition region while being capable of, in use, maintaining the required pressure conditions within the ventilator. Such a seal further reduces discomfort to the patient and eliminates the tendency of tearing of the seal.
According to the present invention, there is provided a cuirass ventilator comprising a shell member having a peripheral edge and a sealing device secured to the peripheral edge, the sealing device comprising a sealing member depending from the peripheral edge of the shell, the sealing member having a sealing region for sealing against a patient""s body, a body portion having a securing region whereat the sealing member is secured to the shell and a resilient pleated region intermediate the sealing region and securing region whereby, in use, the resilience of the pleated region urges the sealing region into sealing engagement with a patient""s body.
Preferably, the pleated region comprises a plurality of pleat portions connected serially at fold regions, a first end pleat portion being contiguous with said body portion at a first end fold region, and a second end pleat portion, opposite said first end portion being contiguous with said sealing region at a second end fold line.
Conveniently the peripheral edge of the shell has a first portion which, in use, is disposed in proximity with the top of a patient""s chest, second and third portions which extend substantially parallel to the patients height and a fourth portion which extends across the abdomen of the patient and the sealing member is so secured to the shell member as to be inwardly directed in the second and third portions and to be downwardly directed towards the chest or respectively abdomen in the first and fourth portions.
Preferably respective transition portions extend contiguously between the first and second, and first and third portions, the transition portions, in use, being disposed in the armpit region of the patient.
Preferably in said transition portions, the sealing member is shaped for resilient conformability with the body of a patient.
Conveniently, said plurality of pleat portions comprises at least two portions.
Advantageously, said plurality of pleat portions comprises four portions.
Advantageously, the shell is provided with a peripheral flange region and the securing region of the sealing device has a counterpart slot for receiving therein the flange region.
Advantageously, the flange region includes a securing lip for retaining the sealing device thereof.
An embodiment of the invention will now be described with respect to the accompanying drawings in which:
According to a second aspect of the present invention there is provided a ventilator sealing device comprising a body portion for securing the sealing device to a peripheral edge of a cuirass ventilator, a sealing region for sealing against a patients body and a resilient pleated region intermediate the body portion and the sealing region.
Advantageously the pleated region comprises a plurality of seal portions connected serially at fold regions, a first end portion of said pleated region being contiguous with said body portion at a first end fold region, and a second end portion, opposite said first end portion being contiguous with said sealing region at a second end fold line.
Preferably the sealing device forms a ring.
According to a third aspect of the present invention there is provided a cuirass ventilator shell having a peripheral edge which is concavo-convex in cross-section, the edge having a hook securing means for a sealing device in accordance with the second aspect of the present invention.